Effect of gallium addition on physical and structural properties of Ge-S chalcogenide glasses

GeS2.5 chalcogenide glass was selected for studying effects of Ga addition on physical and structural properties. Glassy and partially crystallized samples of (100−x)GeS2.5−xGa (5 mol% ≤ x ≤ 40 mol%) were prepared, and their thermal and optical properties were characterized. With increasing Ga content (x), values of Tg and optical band gap of glasses initially increased and then decreased, showing a maximal value at x = 25 mol%, that is, with stoichiometric composition of 85.7GeS2·14.3Ga2S3. These changes were discussed and correlated to evolution of network structure, which was investigated by Raman spectra recorded in glassy matrices of (100−x)GeS2.5−xGa (5 mol% ≤ x ≤ 40 mol%). This work contributes to understanding of composition-structure-property relationship of chalcogenide glasses.